Supercomputers/Systems/Ohtaka
Japan · operational · hpc
Ohtaka
Operated by ISSP Supercomputer Center at ISSP Supercomputer Center .
Phase 1 seed dataset, compiled by hand. These rows were built from public operator, laboratory and vendor sources. A mechanical second-reader pass has since fetched every cited source: 1092 of 1153 systems have a readable citation that names them, and 40 are genuinely weakly sourced. Every claim carries its source and a confidence tier. Treat anything below verified as a lead, not a citation.
Measured performance
- Rmax
- 3.49 PFlop/s
- Rpeak
- 5.12 PFlop/s
- Rmax ÷ Rpeak
- 68.2%
- Cores
- 215,040
- Power
- -
- Per watt
- - GF/W
Figures are as last publicly reported for the configuration described below, not a live measurement. Where a system was upgraded in place, the post-upgrade configuration is shown and the earlier one appears in the timeline.
What this machine is made of
One row per supplier relationship. “Supplier at build” is the company that shipped the part at the time; where that company has since been acquired, the parent it rolls up to today is shown beside it. That distinction is what makes ticker-level aggregation possible across a thirty-year dataset.
| Role | Part | Supplier at build | Quantity | Confidence | Source |
|---|---|---|---|---|---|
| Integrator | - Dell PowerEdge C6525 and R940 | Dell Technologies | - | Reported | top500.orgmdcl.issp.u-tokyo.ac.jp |
| Interconnect | NVIDIA InfiniBand HDR Interconnect Fat tree or dragonfly+ · 200 Gb/s per port · About 0.6 microseconds HDR100 InfiniBand fat tree | NVIDIA | - | Reported | mdcl.issp.u-tokyo.ac.jp |
| Operating system | Red Hat Enterprise Linux Operating systems Linux distribution · Open source, commercial support subscription Red Hat Enterprise Linux | Red Hat | - | Reported | top500.org |
The read
The University of Tokyo's Institute for Solid State Physics system, Dell PowerEdge nodes with AMD EPYC 7702 CPUs and no accelerators on HDR100 InfiniBand, in service since October 2020 and 87th in November 2020. ISSP's page says the CPU node count was cut in July 2026. ISSP is the only source for the operator and dates, and the city is not stated, so no coordinates are recorded. TOP500 is the only source for Rmax, Rpeak and core count, so the tier is reported.
Timeline
Public list appearances
Pointers only: rank and edition, linking to the canonical entry. We do not reproduce list tables. See sourcing policy.
Site & facility
Change history
- 2026-09-20 Added with a rank pointer on the edition where it ranked highest
Source check
We fetched this system's own citations and recorded whether each page actually mentions it. This is a corroboration signal, not a fact check, and it is published so you can see how well the sourcing holds up rather than take it on trust.
| Cited source | Result | Found on the page |
|---|---|---|
| issp.u-tokyo.ac.jp | names system only | - |
| top500.org | names system and part | NVIDIA InfiniBand HDR |
Checked 2026-10-09 by pnpm verify. Re-run it and the table changes with the web.
Further reading
Operating a supercomputer
Acceptance testing, why "installed" and "in production" are six months apart, and the machine lifecycle.
The interconnect
Topologies, why latency and tail behaviour matter more than bandwidth, and how the fabric market consolidated.
Programming a supercomputer
The software stack beneath the application, and why the OS is now a sovereignty signal as much as a technical choice.